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Re: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API



On Sun, 10 Oct 2010 23:08:22 +0900
FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote:

> On Fri, 20 Aug 2010 14:50:12 +0300
> Marin Mitov <mitov@xxxxxxxxxxx> wrote:
> 
> > On Friday, August 20, 2010 11:35:06 am FUJITA Tomonori wrote:
> > > On Fri, 20 Aug 2010 11:13:45 +0300
> > > Marin Mitov <mitov@xxxxxxxxxxx> wrote:
> > > 
> > > > > > This tric is already used in drivers/staging/dt3155v4l.c
> > > > > > dt3155_alloc_coherent()/dt3155_free_coherent()
> > > > > > 
> > > > > > Here proposed for general use by popular demand from video4linux folks.
> > > > > > Helps for videobuf-dma-contig framework.
> > > > > 
> > > > > What you guys exactly want to do? If you just want to pre-allocate
> > > > > coherent memory for latter usage,
> > > > 
> > > > Yes, just to preallocate not coherent, but rather contiguous memory for latter usage.
> > > > We use coherent memory because it turns out to be contiguous.
> > > 
> > > Hmm, you don't care about coherency? You just need contiguous memory?
> > 
> > Yes. We just need contiguous memory. Coherency is important as far as when dma
> > transfer finishes user land is able to see the new data. Could be done by something like
> > dma_{,un}map_single()
> 
> Anyone is working on this?
> 
> KAMEZAWA posted a patch to improve the generic page allocator to
> allocate physically contiguous memory. He said that he can push it
> into mainline.
> 
I said I do make an effort ;)
New one here.

http://lkml.org/lkml/2010/10/12/421

Thanks,
-Kame

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